Generally, cabinet-based DC power systems, with and without batteries, are commercially available from a variety of sources. An AC to DC converter, with or without a battery charger, in a steel cabinet, is also commercially available from a variety of sources. A single steel cabinet mounting more than one AC to DC converter, with or without a battery charger, is also commercially available. An AC to DC converter, with or without a battery charger, and rechargeable batteries in a steel cabinet is commercially available. A combination of multiple chargers, battery sets, or cabinets is commercially available for use in the system. Rechargeable batteries in a steel cabinet may also be used in such systems. Multiple battery shelves installed in a steel cabinet to support rechargeable batteries is another commercially available component.
Other available components or equipment may be installed in existing steel cabinets, including: circuit breakers, vertical rack mount rails that meet EIA standards, inverters (DC to AC converters), relays, voltage monitoring equipment, current shunts, personal computers, and other communications and monitoring equipment. Other parts may include hinged doors, removable panels (full or partial) located on any side or bottom or top, cooling vents, filters, fans, thermometers, mounted on or in these steel cabinet systems.
Other commercially available items include provisions for moving and lifting steel cabinets, including various types of fork lift bases, and top lift features or attachments such as brackets, bolts, or other hardware.
In many existing DC power systems, AC to DC conversion is accomplished by transformer-type Silicon-Controlled Rectifier (SCR) battery chargers that are large, heavy, and inefficient. Newer switched mode converters enable greater power density and less waste heat so as to provide increased energy efficiency. In such switched mode converters, circuitry is used to make an input current waveform as close to sinusoidal as possible and in-phase with a sinusoidal input voltage waveform. This provides reduced (“cleaner”) harmonic content on the AC line and fewer volt-amps wasted (apparent power is much closer to real power). This feature may be referred to as active power factor correction.
Various DC power systems described above are commercially available. In most cases, one or more specifications, measures, or parameters fall short of the desired performance characteristics and attributes in an improved system. Examples include, but are not limited to, the need for multiple systems to perform a function or a lack of integration. For example, a function may be performed in existing systems by a combination of expensive systems, less efficient systems, systems with a lower level of reliability, systems which are more difficult to install and repair, systems that require a longer period of time to repair or to return to service. Existing DC power systems are more difficult to understand and order correctly because of a larger number of model numbers. For example, a user who needs a system that can run on 208 VAC, but who ordered a system that runs on 240 VAC, has ordered the wrong system and the user has to incur the costs of return, restocking charges, reshipment, etc. Further existing systems can not be field-upgraded to produce more DC output power.
No pre-existing cabinet-based DC power system has been qualified, tested, and marked as compliant with International Building Code (IBC) Seismic standards.